Looking back over history to episodes of the state's heartlessness – to the era of slavery, for example, or the enforced separation of families when loved ones were deported for minor crimes and children were taken from their parents – we wonder how society tolerated such cruelty. How did people live so easily with the knowledge of what was going on and ignore unkindness and injustice?

The detention of the children of asylum seekers at Yarl's Wood and all that it involves – the dawn raids by uniformed family snatchers deployed by the UK Border Agency; the separation from toys, schools, new friends and familiar surroundings; the uncertainty; the dread in your parents' eyes and the awfulness of the detention centre – is one of the most palpable wrongs in our society.

Not only is it bewilderingly unkind and lacking in normal humanity, as the story above about the Christmas visit shows, but it is unjust because, of course, none of these children has done anything wrong. Their parents simply want to find sanctuary in Britain, often from the rape, torture, persecution and other horrors that have driven them from their homelands.

For a government that makes so much of protecting children from cruelty and abuse, it seems extraordinary that the central truth about Yarl's Wood is that it damages the thousands of children who have been held there. The Royal College of Paediatrics and Child Health says the detention policy causes children and families "significant harm". Another recent report by paediatricians and psychologists – Child Abuse and Neglect – catalogued an increase in sexualised behaviour, bed-wetting and the soiling of pants.

Yarl's Wood is a prison for people who have not been found guilty of any crime, yet the regime, which includes fingerprinting, roll calls, body searches, ID cards that children must carry at all times and countless locked doors, treats them as criminals, which goes some way to explaining the deterioration in mental health of both parents and children, self-harm and suicide attempts. I was moved recently when listening to an African mother telling a hushed room at a meeting in London how her children's respect for her as a parent had declined because she could do nothing to stop them from being seized and taken to Yarl's Wood.

Even though she has been granted leave to remain, it was extraordinarily difficult for her to regain the standing in her children's eyes and to persuade them that they were safe. The state has no business inflicting this kind of damage on people's relations with their children, particularly because statistics show that parents with children almost never abscond while their case is being assessed. It is simply too difficult.

One has to ask what is in the minds of people like Phil Woolas, the Home Office minister in charge of the UK Border Agency and the policy of child detention, and those who enforce it. Clearly Serco, the company that operates Yarl's Wood, has everything to gain from locking up kids in this dreadful place, but what about the minister who could so easily bring an end to it?

Almost every report on this subject shows that housing asylum seekers in sheltered accommodation, as happens in Australia, is far cheaper and allows families, who have suffered and face uncertainty, a degree of normality while their applications are being assessed. That is the rational and humane way to deal with what has become an avoidable national disgrace.

However, many who campaign on this issue now suspect that the government uses the regime at such places as Yarl's Wood as a deterrent to future asylum seekers. Let us hope that the government, and Mr Woolas in particular, have not sunk to the level of mistreating children to discourage those who, in desperation, ask Britain for sanctuary.